1. Technical Field
The invention pertains to the technical sector of controlled pneumatic devices for the automatic inflation/deflation of a tire, notably, but also of any recipient holding a gaseous fluid under pressure.
2. Description of the Related Art
Such controlled pneumatic appliances for automatic inflation/deflation of a tire are intended to be controlled remotely, notably from the passenger compartment of a vehicle, for example. These devices permit one to adjust the pressure of tires from inside the vehicle, via a simple interaction with a control interface. This is notably very useful for vehicles such as rally, military or agricultural vehicles, of which the tire pressures are generally lower than 5 bar. These devices are generally designed for all drivers of vehicles needing to vary the pressure of the tires. In particular, they allow one to vary the tire pressures so as to be suitable for the surfaces over which the said vehicle is traveling, the loads it is carrying, and the speed at which the vehicle is moving.
Other applications are possible for these devices—notably all applications in which it is necessary to automatically inject or remove, in a controlled manner, a gaseous fluid from a recipient holding the said fluid.
The closest state of the art in this domain, to the applicant's knowledge, is described in the European patent document number EP 0 511 135, of which the present applicant is the holder.
This patent document describes an arrangement of a controlled pneumatic appliance for the automatic inflation/deflation of a tire.
With reference to FIG. 1, this device for the inflation/deflation of a recipient is of a type that includes, firstly, a cavity (1) partitioned by a flexible membrane (2) into two chambers—referred to as the control (3) and exhaust (4) chambers—of which the first communicates with a relative pressurization circuit and the second communicates with a bore (5) connected to the recipient, and with at least one exhaust tube (6) venting externally to the cavity and, in addition, with a flap valve system (7) able to close or open a means of passage at least between the bore and the exhaust tube, and including:                a seat (8) designed to interoperate with an inflation flap valve (9);        a seat (10) connected to the bore (5) and designed to interoperate with an exhaust flap valve (11);        a flexible component (12) tending to maintain the inflation flap valve (9) in the closed position on the seat (8);        a flexible component (13) tending to maintain the exhaust flap valve (11) in the closed position on the seat (10).        
This device of prior art is remarkable in that:                the seat (8) is presented by the membrane (2) in the control chamber (3);        the inflation flap valve (7) and the exhaust flap valve (11) are mounted in opposition, either side of the membrane (2), and are sensitive to the position of the said membrane, such as to form a mobile assembly of two flap valves servocontrolled by the membrane (2);        and in that the flexible component (13) is associated with the membrane (2);        
and in that a travel limiter (14) is incorporated, limiting the travel of the assembly during the opening of the exhaust flap valve (11).
One disadvantage of this device is that its arrangement is implemented in a manner that the deflation of the recipient occurs at low pressure. This means that it is impossible, when the said device interoperates with a measuring device, to be able to take a measurement at low pressure. This is because if one wants to take a measurement of a relatively low pressure, one would change directly to the tire deflation phase instead of taking the measurement. Many vehicles use low inflation pressures of less than 5 bar—notably agricultural vehicles, vehicles for geological research, four-wheel-drive vehicles, etc.